1. Field of the Invention
This invention relates to a system for automatically analyzing the contaminants in the exhaust gas emissions from a motor vehicle only when the exhaust gas input thereto is not blocked.
2. Description of the Prior Art
As a result of the increase in public concern over environmental pollution, governmental agencies and private citizens have joined in passing legislation which will limit the concentration of selected exhaust gas contaminants in the emissions from motor vehicles. A number of systems for measuring the concentration of contaminants in the exhaust gas emissions from motor vehicles have been developed. Many of the gas analysis systems do not have sufficient accuracy and do not produce consistent contaminant level readings. Many other exhaust gas analysis systems use analog outputs such as meters, most of which are nonlinear in their response and require continuous adjustment. Automated systems, however, can provide faulty results if the exhaust gas inputs thereto become blocked, which allows, willful false testing and/or erroneous indication of unnecessary repair.